Effect of Extrusion Temperature and Feed Moisture Content on the Microstructural Properties of Rice-Flour Pellets and Their Impact on the Expanded Product

Yadira Zambrano, Ingrid Contardo, María Carolina Moreno, Pedro Bouchon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Extrusion can lead to an expanded product or to a slightly expanded pellet, known as a third-generation (3G) snack. In this case, expansion occurs subsequently, in an independent thermal device (e.g., oven), out of the extruded pellet. During both processes, several structural changes occur which are linked to processing conditions, including cooking temperature, screw speed, formulation, and initial moisture content. However, a clear relationship between processing variables and the structure of pellets and expanded products has not yet been identified. Accordingly, this work aimed to study the effect of extrusion temperature (110, 135, and 150C) and moisture content (27, 29, and 31%) in rice-flour pellets and their microwave expansion, through a microstructural approach using micro-CT. The results showed that the lowest moisture content (27%) and the highest extrusion temperature (150C) led to the highest pellet volume and the highest wall thickness, which in turn led to the highest expansion after microwave heating (50 s, 800 W). Interestingly, no significant differences were observed when analyzing the ratio between the volume of the expanded products and the volume of the pellet (~2.4) when using the different processing conditions.

Original languageEnglish
Article number198
JournalFoods
Volume11
Issue number2
DOIs
StatePublished - 12 Jan 2022

Bibliographical note

Funding Information:
Funding: The financial support of ANID through Fondecyt Project number 1210709 and through Doctoral Fellowship 2019 (Folio no. 21191208) from the Advanced National Human Capital Formation Program is acknowledged.

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • 3G snacks
  • Extrusion
  • Micro-CT
  • Microstructure
  • Rice
  • X-ray

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